Many fluid food products are aseptically processed to prevent the undesirable effects of microorganism. Aseptic processing can significantly extend the shelf life of most foodstuffs and often involves the continuous sterilization of a fluid food product circulated within a closed process system. In a typical aseptic process, a fluid food product is thermally pasteurized by heating to an elevated temperature for a duration sufficient to reduce the viability of microorganism to acceptable levels. Following pasteurization, the fluid food product is typically transported through a cooling media before packaging into a sterile container. One example of such a system is shown and described in U.S. Pat. No. 5,802,96, which is assigned to the assignee of the present invention. In most processing and packaging operations, the cooling side of the system is much more prone to contamination by microorganism. One potential point of contamination is the occasional requirement to draw off a quantity of sterile product or other media from the sterile atmosphere of an aseptic cooling system to an unsterile atmosphere, such as an open tank or gutter. Over time, microorganisms can migrate up the discharge line and contaminate the system.
Conventional valves produce a fluid tight seal between a movable valve member and a complementary valve seat so as to discontinue or restrict flow. Absent suitable precautions, microorganisms resident in the discharge line downstream of the discharge valve can readily traverse the fluid-tight seal, invade the sterile piping system, and compromise the sterility of the closed process system.
Various manners of dealing with contamination issues in food processing systems have been utilized in the past. One typical system is a double block and bleed valve system which involves using two spaced apart valves in the discharge line with steam injection between the two valves. The valves are sequentially opened and timed with the introduction of stream to maintain sterility at the outlet. Unfortunately, this type of system is rather complicated and still may not maintain optimum sterility at the discharge location.
It would there fore be desirable to provide a product discharge valve, especially useful in the fluid food product industry, which combines simplicity of design with effective sterilization of the discharge location.